One of the causes of the noises generated by a pneumatic tire is cavernous resonance resulting from vibration of the air with which the tire is filled. When a tire is rolled, uneven road surfaces cause a tread portion to vibrate. The vibrations of the tread portion cause the air inside the tire to vibrate, which produces this cavernous resonance.
As a method for reducing noise caused by such cavernous resonance, providing a sound absorbing member within a cavity portion formed between the tire and the rim of the wheel has been proposed. More specifically, a band-like sound absorbing member is bonded to a region of the tire inner surface corresponding to the tread portion (for example, see Japanese Unexamined Patent Application Publication Nos. 2002-67608A or 2005-138760A).
However, with a configuration in which the sound absorbing member is bonded to the tire inner surface in order to reduce cavernous resonance, when the heat generated in the pneumatic tire is increased due to high-speed traveling, heat dissipation from the tread portion into the tire cavity is impeded by the thermal insulation effect of the sound absorbing member, so heat tends to accumulate in the tread portion. Such an increase in the temperature of the pneumatic tire causes a problem that high-speed durability is deteriorated.